Strings with '%' symbols which aren't token placeholders don't format correctly

[lawmaestro]

For instance the following:
"%s 0% fat Greek style yogurt"
when formatted with:
"60ml"
should ideally result in:
"60ml 0% fat Greek style yogurt"
Instead the outcome is nil

I've taken a look over the code and this could be fixed by tweaking line 587 in Sprinter.swift:
if first == "%" { break }
to become:

if first == "%" {
  if string.last == nil || string.last == " " {
    break
  }
}

I've tested this locally and all unit tests pass with the change (as well as this new case). I'm happy to create a PR? Let me know, cheers.

[nicklockwood]

Yes, please do.

I need to check the spec for what the expected behavior is here. I would think you are supposed to write %% in this case and that a % on its own is a syntax error, but in a case like this it seems reasonable to allow it.

[lawmaestro]

The problem with that approach is that it would break formatting for tokens inlined, for example:
Hello_%s_world

The approach I took to work around the problem initially was to swap out the '%' I wanted ignoring for a 'widepercent'. An alternative as you say could also be to double it up - '%%'. Would be nice to be able to defend against it in the formatting though :/

[nkalvi]

According to the standard

Each conversion specification is introduced by the character ( '%' ). After the character '%', the following shall appear in sequence:
...
%: Write a '%' character; no argument is converted.

So, using %% here is expected.